The prior art is best exemplified by systems for allowing airplane flight crew members to designate their preferred lines of flying ("LOF") assignments and rank them in a preferred order for presentation to the employer. In the prior art systems, the employees are presented with a database searching tool to help them identify their preferred assignments. The searching tool allows them to work with a manageable number of criteria, such as twelve, each of which can be compared with each assignment to determine whether the assignment meets that criterion. The prior art methods fall in one of three categories.
The first category is known as the Priority Method. In this method, the employees are required to give a priority ranking to the criteria. A database search is then initiated. The assignments are presented in a ranked list. Those assignments, if any, which meet all the criteria are listed first. Those which meet all the criteria except for the last priority criterion are presented second. Those assignments which meet all criteria except the last two priority criteria are listed third; and so forth. Last on the list are assignments which meet none of the criteria, and next to last on the list are assignments which meet all but the highest priority criterion.
The system assumes that the resulting list is in the order desired by the employee. However, if it is not, the employee can use an editor to adjust the sequence of the assignments. If the employee knows of certain desired assignments before using the database searching tool, those assignments can be placed at the head of the list before the search is commenced. Alternatively, they can be moved to the head of the list after the search is completed if the employee can find them in the list.
In the Priority Method, if a particular assignment meets all the criteria except the highest priority criterion, it is at the bottom of the list, lower than other assignments which fail to meet more than half of the criteria. This system is deficient because seldom, if ever, in the judgment of employees, is there an absolute hierarchy of criteria. Rather, an assignment which meets most of their criteria is preferred over an assignment which meets only one of their criteria, even if that criterion is their highest priority criterion.
The second category is known as the Scoring Method. Each of various criteria is given a score. The computer system then searches the database and calculates a total score for each of the assignments. It then ranks them in the order of highest to lowest score. Like the Priority Method, this method performs one search for attractive assignments using one set of criteria. It does not allow the employee to conduct two searches with inconsistent sets of criteria, both of which might be attractive to the employee.
The third category is known as the Matching Method. This method places at the top of the list those assignments which meet all of the criteria, then places second those that meet all but one of the criteria, with a secondary ranking within the group according to the relative importance of which criteria was not met, etc.
Under the prior art systems, it is not possible to adjust one or more criteria to make them less restrictive and perform additional searches to find other assignments which meet the somewhat less restrictive criteria. Each criterion may be specified only once as a single value. Once all the criteria are specified, each of the prior art systems performs one search and selection process.